The Fracture, or what could be simply looked at the division of Earuth, or at the time, Ear-du-roth, into dozens of independent worlds spread throughout the cosmos, is believed to have occurred around 7000 BD. This would have been after 1000 years of fighting between the Inferi, their children, and humans, or Yune’s Second Children.
The actual explosion that shattered Ear-du-roth was the result of Yune’s anger. It is believed, as mentioned in the epic poem, The Fairy and the Human*, and in more detail, in the story, The First Sun after Daruk-sec-sho**, that Yune channeled his magic into the great tree of the Garden, Yalen-bon-afkan. Through its roots, this tree held the world of Ear-du-roth together. Yune’s magic, traveling down the trunk and through the roots, ripped the world apart, the force of which cast the broken shards of Ear-du-roth through the cosmos and, in some cases, through the Veil to other realities and universes.
For quite some time, maybe until even 1000 UD, passages existed between the shards allowing for travel and trade between the races. But during the Age of Redemption (or the Age of Man), these passages have seemed to have been closing at a steady rate. It is believed that by 890 UD, or perhaps even sooner, that there will be no more ways to travel between the shards.
* There has not been a complete version of this poem found, only segments. One such segment, thought to be near the middle of the poem, describes the Fracture in lyrical details.
** Although a work of narrative fiction, it is believed by scholars that this is the closest representation to the actual event